According to Professor Gary Shaffer of the University of Copenhagen we should stop burning fossil fuels now so that we will have enough coal, oil, and gas left when we need to fend off the next ice age over the next several hundred thousand years:
…for a management scenario whereby fossil fuel use was reduced globally by 20% in 2020 and 60% in 2050 (compared to 1990 levels), maximum global warming was less than one degree Celsius above present. Similar reductions in fossil fuel use have been proposed by various countries like Germany and Great Britain.
In this scenario, combustion pulses of large remaining fossil fuel reserves were then tailored to raise atmospheric CO2 content high and long enough to parry forcing of ice age onsets by summer radiation minima as long as possible. In this way our present equable interglacial climate was extended for about 500,000 years, three times as long as in the “business as usual” case.
Nice to see some people are cranking up their Buxton indices into the 100, 000 years range.
[via FuturePundit][image from nick russill on flickr]
A study suggests that long-term changes in the Earth’s orbit would have resulted in an ice age between 10,000 and 100,000 from now, if it were not for the effect of anthropogenic global warming:
The chill would induce a long, stable period of glaciation in the mid-latitudes, smothering Europe, Asia and North America to about 45-50 degrees latitude with a thick sheet of ice.
However, there is now so much CO2 in the air, as a result of fossil-fuel burning and deforestation, that this adds a heat-trapping greenhouse effect that will offset the cooling impacts of orbital shift, said Crowley.
“Even the level that we have there now is more than sufficient to reach that critical state seen in the model,” he said. “If we cut back [on CO2] some, that would probably still be enough.“
Apparently this isn’t an excuse to continue venting CO2:
Crowley cautioned those who would seize on the new study to say “‘carbon dioxide is now good, it prevents us from walking the plank into this deep glaciation’.”
“We don’t want to give people that impression,” he said. “(…) You can’t use this argument to justify [man-made] global warming.”
[story at Physorg][image from Pear Biter on flickr]